Physics of Plasmas
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Phase-locking of tearing modes in the reversed field experiment

Phys. Plasmas 9, 2707 (2002); doi:10.1063/1.1481057

Issue Date: June 2002

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Richard Fitzpatrick
Institute for Fusion Studies, Department of Physics, University of Texas at Austin, Austin, Texas 78712

Paolo Zanca
Conzorzio RFX, Corso Stati Uniti 4, 35127 Padova, Italy
In the reversed field experiment (RFX) [F. Gnesotto et al., Fusion Eng. Des. 25, 335 (1995)], the m = 1 and m = 0 tearing modes present in the plasma are observed to phase-lock together to form a highly peaked, strongly toroidally localized, pattern in the perturbed magnetic field. This pattern, which is commonly known as the "slinky" pattern, gives rise to severe edge loading problems which limit the maximum achievable toroidal current. A theory is presented which explains virtually all salient features of the RFX slinky pattern. The central premise of this theory is that at high ambient mode amplitude the various tearing modes occurring in the plasma phase-lock together in a configuration which minimizes the magnitudes of the electromagnetic torques exerted at the various mode rational surfaces. The theory successfully predicts the profiles of the edge radial and toroidal magnetic fields generated by the m = 0 and m = 1 modes, the phase relations between the various modes, the presence of a small toroidal offset between the peaks of the m = 0 and m = 1 contributions to the overall slinky pattern, and the response of the pattern to externally generated m = 0 and m = 1 magnetic perturbations. ©2002 American Institute of Physics.
History: Received 22 October 2001; accepted 2 April 2002
Permalink: http://link.aip.org/link/?PHPAEN/9/2707/1
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KEYWORDS and PACS

Keywords
PACS
  • 52.35.Py
    Physics of plasmas and electric discharges Waves, oscillations, and instabilities in plasmas and intense beams Macroinstabilities (hydromagnetic, e.g., kink, fire-hose, mirror, ballooning, tearing, trapped-particle, flute, Rayleigh-Taylor, etc.)
  • 52.35.Mw
    Physics of plasmas and electric discharges Waves, oscillations, and instabilities in plasmas and intense beams Nonlinear phenomena: waves, wave propagation, and other interactions (including parametric effects, mode coupling, ponderomotive effects, etc.)
  • 52.55.Hc
    Physics of plasmas and electric discharges Magnetic confinement and equilibrium Stellarators, torsatrons, heliacs, bumpy tori, and other toroidal confinement devices
  • YEAR: 2002

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ISSN:
1070-664X (print)   1089-7674 (online)
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REFERENCES (31)
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